Dynamics of spiral waves in excitable media with local time-periodic modulation

The propagation of spiral waves in excitable media with locally inhomogeneous time-periodic modulations is studied numerically, and it is shown that the size of the local inhomogeneity and the amplitude and frequency of the periodic forcing play a major role in determining the spiral wave dynamics, suppression and breakup. It is also shown that, in the absence of breakup, spiral waves flatten and thicken as the size of the inhomogeneity is increased, and that spiral waves may penetrate into the modulation region if the forcing frequency is sufficiently small. At high frequencies, however, it is shown that the inhomogeneity behaves as an obstacle. It is also reported that, for sufficiently large modulation regions, the spiral wave may be annihilated and become an almost cylindrical wave with initially high concentration of the activator in the center of the inhomogeneity.